The objective of the proposed research is to ultrastructurally characterize eukaryotic gene and viral transcription, nascent transcript processing, chromatin replication and structure, and mRNA translation. Ultrastructural observations will be supplemented with biochemical approaches, and both will be related to the regulatory phenomena involved in these basic genetic processes. Emphasis will be on characterizing specific genes and their products, including transcription of myeloma cell immunoglobulin genes, translation of the mRNA of the silk fibroin gene of Bombyx mori, transcription of adenovirus genes in infected HeLa cells and processing of viral transcripts, chromatin structure in amphibian and avian ribosomal genes, and polymerase structure in 5S rRNA genes of Xenopus. Other cell types that will be used are Drosophila embryos (transcription, replication, nascent ribonucleoprotein structure), amphibian oocytes (transcription, stored mRNA), and sea urchin oocytes (stored maternal mRNA, translation, oogenetic transcriptional patterns). The methods that will be used include high resolution bright and darkfield electron microscopy, immunoelectron microscopy, electron microscopic autoradiography, isolation of cellular and nuclear components by centrifugation and chromatography procedures, in vitro transcription of defined genes on plasmid vectors in Xenopus nuclear extract, restriction endonuclease and other enzymatic digestion and other chemical probes of structural organization. We hope to gain new information on the transcription unit structure of defined genes, the interactions within RNA polymerase-chromatin template-nascent product complexes, nuclear packaging and processing of RNA, interactions between ribosomes and mRNP complexes, and the localization of specific proteins on DNA and RNA.